External loading test apparatus

ABSTRACT

External External loading test apparatus comprising:
         a structure with at least three pillars supporting a platform, the platform being configured to receive a podded electric propulsion motor in a hanging position while allowing operation of said pod,   at least a test subsystem, for applying a force on the pod to simulate full scale external loading.

The present invention relates to full scale test rigs, in particular,test rigs for conducting external load testing of ship propeller pods,in particular ice loading tests.

In order to improve steering of large ships, thrust vectorization isbecoming increasingly common. Such vectorization enables using the mainpropulsion propeller for lateral or reverse movement. In order toachieve such a vectorization, the main propeller is fitted on a podenabling transmission of engine power while allowing rotation of thepropeller direction.

Strict regulation requires that such pods are able to withstand thepressure of ice blocks that can be encountered in artic seas.

Up to now, compliance with said regulations were achieved thanks to acombination of design safety margins and trials on scaled downprototypes, within a statistical approach. Such trials are commonlycalled ice loading tests.

However, clients now commonly require that each pod is guaranteed forcompliance. Individual testing of each pod is therefore required. It isalso required that the testing is performed before it is fitted in orderto avoid damages to the ship.

From the state of the art, the following documents are known.

Document WO2019-011927A1 discloses a method for determining thedirection and the amplitude of a force applied to a propulsion nacelle,comprising stress direction identification.

Document CN103913291 discloses a pod propelling system testing devicecomprising means for measuring torque and thrust created by a podpropelling system.

No test rig able to perform full scale external load testing on apropeller pod exists.

An object of the invention is an external loading test apparatuscomprising a structure with at least three pillars supporting aplatform, the platform being configured to receive a podded electricpropulsion motor in a hanging position while allowing operation of saidpod, at least a test subsystem, for applying a force on the pod tosimulate full scale external loading.

A test subsystem can comprise a pod actuator interface, an actuator andan actuator structure interface, the actuator structure interfacecomprises a frame intended to be removably fixed to the structure andmeans forming a rotational joint with the actuator, so that the actuatoris anchored to the structure while retaining at least one degree ofrotation, the actuator comprising an actuator body and an actuator rodconfigured so that the actuator rod extends from or retracts into theactuator body upon command.

The pod actuator interface can comprise a bore for mating with a podoutput shaft on one side and an actuator rotational joint with theactuator rod on the opposite side.

A torque measurement device can be fitted on a test subsystem, thetorque measurement device comprising two connecting rods connecting thepod actuator interface to the structure along with force sensors affixedon each connecting rod, the torque being determined based on themeasured forces, the dimensions of the connecting rods and thedimensions of the test apparatus.

The force can be applied on a direction different from the direction ofthe pod output shaft.

The pod actuator interface can comprise a plate fitted with a pod shapecompensating element in contact with the pod on one side and arotational joint with the actuator rod on the opposite side.

The actuator structure interface can comprise a frame or a beam forremovably fixing the test subsystem to the structure.

A test subsystem can apply the force along a direction sensibly matchingthe direction of the pod output shaft.

A test subsystem can apply the force along a vertical direction.

The test subsystem actuator can be a hydraulic jack, a magnetic actuatoror an Archimedes screw.

The pod can be rotatably fixed to the platform, the pod rotationcontributing to apply the force on different directions.

The test subsystems can be removably fixed to the structure.

The test apparatus can comprise command means for commanding therotation of the pod, the at least one actuator, and, when applicable,the force sensors.

The command means can be able to perform continuous, variable or cyclicexternal loading.

The test apparatus can be used for ice loading testing.

The present invention will be better understood from studying thedetailed description of a number of embodiments considered by way ofentirely non-limiting examples and illustrated by the attached drawingin which:

FIG. 1 shows an embodiment of the external loading test apparatus,

FIG. 2 shows an axial test subsystem,

FIG. 3 shows a lateral test subsystem, and

FIG. 4 shows an axial testing subsystem fitted with a torque measurementsystem.

Ice loading test is a particular case of external loading test, whereinan external load is applied to a podded electric propulsion motor.

The external loading test apparatus described herein present theadvantage to be self-supporting as it does not require complex civilengineering works prior to operation. It does not require either thatthe civil engineering works are resilient to the reaction forcesinvolved in the testing.

The external loading test apparatus comprises a structure with at leastthree pillars supporting a platform receiving a podded electricpropulsion motor (“pod”) and providing the auxiliary systems requiredfor operating said pod, in particular hydraulic and electric power. FIG.1 illustrates a particular embodiment of the external loading testapparatus 1 with four pillars 2.

More particularly, the platform 3 comprises a collar mating with acomplimentary collar on the pod 4, and allowing both securing androtating the pod. At least one of the collars comprises a bearingallowing lasting rotating capabilities. Mating can be achieved bybolting. Once fixed to the platform, the propeller pod hangs below theplatform in a way similar to the way it is fitted on a ship. Sucharrangements are considered standard practice for fitting a pod on theouter hull of a ship and are therefore not described further.

The structure 2,3 can be fitted with different subsystems 5 a, 5 b forexternal loading tests, in particular an axial test subsystem 5 a and/ora lateral test subsystem 5 b. Thanks to the collar and the auxiliarysystems, the pod can be operated and rotated as it would be on a ship.The rotation of the pod combined with the placement of different testsubsystems 5 a, 5 b enables external loading tests on the pod alongdifferent directions. External loading can also be applied to the podpropeller.

FIG. 2 illustrates the axial test subsystem 5 a as an exploded view. Itcomprises a pod actuator interface 6 a, and an actuator 7 a and anactuator structure interface 8 a.

The pod actuator interface 6 a fits on the pod output shaft upon whichthe propeller is destined to be fitted. On a side, the pod actuatorinterface 6 a thereby comprises a bore similar to the bore present onthe propeller so that it can be secured on the pod shaft. On an oppositeside, the pod shaft actuator interface 6 a comprises a rotational jointwith the actuator. On FIG. 2, the rotational joint comprises two pinholes 61 a designed to cooperate with both a corresponding bore 70 ainto an actuator rod and a pin 60 a.

The actuator 7 a comprises an actuator body 71 a and an actuator rod 72a, the rod extending from or retracting into the actuator body uponcommand. The actuator comprises the bore 70 a at the actuator rod freeend and two gudgeons 73 a apart from the actuator body 71 a. When theactuator is extending, distance between the bore and the gudgeonsincreases. The gudgeons are part of a second rotational joint with theactuator structure interface 8 a. The external loading test apparatus isnot limited to using a trunnion joint for the second rotational joint asrepresented on FIG. 2.

The actuator structure interface 8 a enables anchoring the actuator body71 a to the external loading test apparatus structure 2,3 so that aforce is produced on the pod output shaft when the actuator rod isextending.

In order to do so, the actuator structure interface 8 a comprises aframe 80 a intended to be removably fixed to the structure 2,3 alongwith two half cylinders 81 a linked to the frame by supporting members82 a. The half cylinders form a trunnion bearing (or trunnion joint)with the two gudgeons on the actuator body. Other forms of rotationaljoint can be used in replacement to the trunnion bearing. Thanks to thetrunnion joint, the actuator is able to rotate around an axis extendingthrough the gudgeons and the half cylinders. Such a rotation enables theaxial test subsystem to accommodate different angles between the podoutput shaft and the platform.

In a particular embodiment, the structure comprises multiple fixationpoints for the actuator structure interface, so that it can be fitted atdifferent distances relative to the platform. It enables the testsubsystem to accommodate different sizes of pods.

FIG. 3 illustrates an exploded view of a lateral test subsystem 5 b. Thelateral test subsystem comprises a pod actuator interface 6 b, anactuator 7 b and a structure actuator interface 8 b, and is thus similarto the axial ice loading subsystem 5 a.

On a side, the pod actuator interface comprises two pin holes 60 bdesigned to cooperate with both a corresponding bore 70 b into an end ofthe actuator and a pin 61 b. Such an arrangement allows for securing theconnection between the pod actuator interface and the actuator whileallowing one degree of rotation. As previously stated, such anarrangement is an example of a rotational joint that can be used in thetest subsystem. Other rotational joints can be considered as long asthey withstand the forces involved.

An opposite side of the pod actuator interface comprises a plate 62 band a pod shape compensating element 63 b stacked above said plate, sothat the actuator applies a force on the plate, the plate applying aforce on the pod shape compensating element, which, in turn, applies aforce on the pod casing. Depending on the shape of the pod casing, thepod shape compensating element 63 b can present a complex shape in orderto mate both the shape of the casing and the orientation of the plate.It can also be made of a compressible or deformable material so that itsshape is altered under applied pressure to match the shape of thecasing.

The actuator 7 b comprises an actuator body 71 b and an actuator rod 72b, the rod extending from or retracting into the actuator body 71 b uponcommand. The actuator 7 b comprises a bore 70 b at the actuator rod freeend and two gudgeons 73 b apart from the actuator body. When theactuator is extending, distance between the bore and the gudgeonsincreases.

The actuator structure interface 8 b comprises a frame 80 b intended tobe removably fixed to the structure along with two half cylinders 81 blinked to the frame by supporting members. The half cylinders form atrunnion bearing with the two gudgeons of the actuator. Rotational jointdifferent than the trunnion bearing can be considered.

Depending of the number and placement of the structure pillars 2, theactuator structure interface 8 b comprises a beam 83 b linking the frame80 b to supporting members 82 b as an arm. In a particular embodiment,the beam 83 b is removably fixed to the frame 80 b so that the distanceof the actuator in regard to the platform 2 can be adapted. It enablesthe lateral test subsystem to accommodate different sizes of pods.

In a particular embodiment, the actuator comprises a second pair ofgudgeons 74 b each apart from the actuator body, and the actuatorstructure interface comprises a second pair of half cylinders 85 b. Insuch an embodiment, two trunnion bearings are therefore formed betweenthe actuator 7 b and the actuator structure interface 8 b, locking theangle of the actuator relative to the platform. In yet anotherembodiment, the actuator structure interface comprises a plurality offirst pair of half cylinders and/or a plurality of second pair of halfcylinders so that each pair of actuator gudgeons can engage two pairs ofhalf cylinders each at different distances in regard to the platform.Such an arrangement allows achieving different angles between theplatform and the actuator with a single lateral test subsystem based onthe spacing between the pairs of gudgeons and the distance between thepairs of half cylinders.

Each test subsystem can be fitted with a torque measurement system,comprising two rigid connection rods extending between the pod actuatorinterface and the structure. At least a force sensor, like a straingauge or a deformation gauge, is affixed on each connection rod,preferably at equal distance of the rod ends. The torque can then inturn be determined based on the dimensions of the connecting rods, ofthe pod actuator interface and of the structure along with the forcesmeasured. FIG. 4 illustrates an axial testing subsystem fitted with atorque measurement system comprising two rigid connection rods 90 a, 91a.

Another embodiment of a test subsystem is connected to the structure sothat the actuator is positioned under the pod in order to apply theforce sensibly vertically. In such an embodiment, a frame is preferredas a structure actuator interface.

The embodiments described above involve using an actuator for applyingpressure on the pod. However, different actuators can be used, inparticular hydraulic, magnetic or mechanical actuator. An example of ahydraulic actuator is a jack. An example of a mechanical actuatorinvolves using an endless screw or Archimedes screw for applying forceson the pod jack interface.

The external loading test apparatus comprises a command system forcommanding the rotation of the pod, the actuators, and, when applicable,the force sensors. It allows an open look or a close loop operation ofthe external loading test apparatus. Operation can be supervised orautonomous. Continuous, variable or cyclic external loading can beachieved.

The external loading test apparatus allows for applying a large range offorces, from few N to MN.

The external loading test apparatus as described above, does not requirecomplex civil engineering works, as it is self-supporting. However, insome embodiments, a vertical test subsystem can be anchored to the civilengineering works below the external loading test apparatus instead ofbeing fixed to the structure.

Finally, when comprising multiple test subsystems, the external loadingtest apparatus is able to simultaneously combine multiple directions offorces applied on the pod and/or its propeller for more complex testingschemes.

1. External loading test apparatus comprising: a structure with at leastthree pillars supporting a platform, the platform being configured toreceive a podded electric propulsion motor in a hanging position whileallowing operation of said pod, at least a test subsystem, for applyinga force on the pod or pod propeller to simulate full scale externalloading.
 2. The test apparatus of claim 1, wherein a test subsystemcomprises a pod actuator interface, an actuator and an actuatorstructure interface, the actuator structure interface comprises a frameintended to be removably fixed to the structure and means forming arotational joint with the actuator, so that the actuator is anchored tothe structure while retaining at least one degree of rotation, theactuator comprising an actuator body and an actuator rod configured sothat the actuator rod extends from or retracts into the actuator bodyupon command.
 3. The test apparatus of claim 1, wherein the pod actuatorinterface comprises a bore for mating with a pod output shaft on oneside and an actuator rotational joint with the actuator rod on theopposite side.
 4. The test apparatus of claim 3, wherein a torquemeasurement device is fitted on a test subsystem, the torque measurementdevice comprises two connecting rods connecting the pod actuatorinterface to the structure along with force sensors affixed on eachconnecting rod, the torque being determined based on the measuredforces, the dimensions of the connecting rods and the dimensions of thetest apparatus.
 5. The test apparatus of claim 3, wherein the force isapplied on a direction different from the direction of the pod outputshaft.
 6. The test apparatus of claim 1, wherein the pod actuatorinterface comprises a plate fitted with a pod shape compensating elementin contact with the pod on one side and a rotational joint with theactuator rod on the opposite side.
 7. The test apparatus of claim 1,wherein the actuator structure interface comprises a frame or a beam forremovably fixing the test subsystem to the structure.
 8. The testapparatus of claim 1, wherein a test subsystem applies the force along adirection sensibly matching the direction of the pod output shaft. 9.The test apparatus of claim 1, wherein a test subsystem applies theforce along a vertical direction.
 10. The test apparatus of claim 2,wherein the test subsystem actuator is a hydraulic jack, a magneticactuator or an Archimedes screw.
 11. The test apparatus of claim 1,wherein the pod is rotatably fixed to the platform, the pod rotationcontributing to apply the force on different directions.
 12. The testapparatus of claim 1, wherein the test subsystems are removably fixed tothe structure.
 13. The test apparatus of claim 1, comprising commandmeans for commanding the rotation of the pod, the at least one actuator,and, when applicable, the force sensors.
 14. The test apparatus of claim13, wherein the command means are able to perform continuous, variableor cyclic external loading.
 15. The test apparatus of claim 1, whereinthe test apparatus is used for ice loading testing.